Dielectric particles, dielectric ceramic composition, and method of production of same

Abstract

Dielectric particles including a main component including barium titanate and R oxide (where R is at least one element selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), wherein when defining the size of the dielectric particles as “D” and defining the region of a depth from the particle surface of 0% to 10% of said D as a surface region, a region of a depth from the particle surface of more than 10% to less than 40% of the D as an intermediate region, and a region of a depth from the particle surface of 40% to 50% of the D as a center region, in the surface region, the ratio of content of the R oxide decreases from the surface side toward the center of the dielectric particles and in the center region, the ratio of content of the R oxide increases from the surface side toward the center of the dielectric particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Below, embodiments of the present invention will be explained in detail based on the drawings, in which:

FIG. 1 is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a conceptual view for explaining the internal structure of a dielectric particle according to an embodiment of the present invention, and

FIG. 3 and FIG. 4 are graphs showing the relationships between the depths from the surface to center of the dielectric particles and the ratios of content of R oxide (Y oxide) of examples and comparative examples of the present invention.

Claims

1. Dielectric particles including a main component including barium titanate andR oxide (where R is at least one element selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), wherein,when defining the particle diameter of said dielectric particles as “D” anddefining the region of a depth from the particle surface of 0% to 10% of said D as a surface region, a region of a depth from the particle surface of more than 10% to less than 40% of said D as an intermediate region, and a region of a depth from the particle surface of 40% to 50% of said D as a center region,in said surface region, the ratio of content of said R oxide decreases from the surface side toward the center of said dielectric particles andin said center region, the ratio of content of said R oxide increases from the surface side toward the center of said dielectric particles.

2. The dielectric particles as set forth in claim 1, wherein, when defining the average number of moles of said R oxide converted to R elements with respect to 100 moles of said barium titanate in said dielectric particles as a whole as Mave, said Mave is more than 0 mole and not more than 0.5 mole.

3. The dielectric particles as set forth in claim 1, wherein, relating to the ratio of content of said R oxide in said surface region, when defining the numbers of moles of said R oxide converted to R elements with respect to 100 moles of barium titanate at the depths of 0% and 10% of said D as M0 and M10 respectively, the ratio M0/M10 is 1 to 30 (however, not including 1).

4. The dielectric particles as set forth in claim 1, wherein, relating to the ratio of content of said R oxide in said center region, when defining the numbers of moles of said R oxide converted to R elements with respect to 100 moles of barium titanate at the depths of 40% and 50% of said D as M40 and M50 respectively, the ratio M50/M40 is 1 to 100 (however, not including 1).

5. The dielectric particles as set forth in claim 1, wherein the numbers of moles of said R oxide converted to R elements with respect to 100 moles of barium titanate at said intermediate region is a range of 0.2 to 8.0 times said Mave.

6. A method of production of a dielectric ceramic composition having a main component including barium titanate anda fourth subcomponent including R oxide (where R is at least one element selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Ym, Yb, and Lu), comprisinga step of preparing a reacted material obtained by reacting the material of said main component and at least part of the material of said fourth subcomponent in advance,a step of adding said reacted material and the remainder of the material of said fourth subcomponent to be included in said dielectric ceramic composition to obtain a dielectric ceramic composition powder, anda step of firing said dielectric ceramic composition powder, whereinany dielectric particles of claim 1 is used as said reacted material.

7. The method of production of a dielectric ceramic composition as set forth in claim 6, wherein the content of said fourth subcomponent in the finally obtained dielectric ceramic composition converted to R elements is 0.1 to 10 moles with respect to 100 moles of said main component.

8. The method of production of a dielectric ceramic composition as set forth in claim 6, wherein the ratio of said fourth subcomponent included in said reacted material converted to R elements with respect to 100 moles % of the total of said fourth subcomponent to be finally included in said dielectric ceramic composition is 0 mole % to less than 50 mole %.

9. The method of production of a dielectric ceramic composition as set forth in claim 6, wherein said dielectric ceramic composition further includes a first subcomponent including at least one type of compound selected from MgO, CaO, BaO, and SrO,a second subcomponent including mainly SiO2 and at least one type of compound selected from MO (where M is at least one type of element selected from Mg, Ca, Ba, and Sr), Li2O1 and B2O3, anda third subcomponent including at least one type of compound selected from V2O5, MoO3, and WO3,the ratios of the subcomponents to 100 moles of said main component beingfirst subcomponent: 0.1 to 5 moles,second subcomponent: 0.1 to 12 moles,third subcomponent: 0 to 0.3 mole (however not including 0).

10. The method of production of a dielectric ceramic composition as set forth in claim 6, wherein said dielectric ceramic composition further includes-a fifth subcomponent including at least one compound selected from MnO and Cr2O3, and a ratio of the fifth subcomponent to 100 moles of said main component is 0.05 to 1.0 mole.

11. The dielectric ceramic composition produced by the method as set forth in claim 6.

12. An electronic device having dielectric layers comprised of the dielectric ceramic composition as set forth in claim 11.